Many police officers turn to extortion, he said, because their supervisors threaten to transfer them to dangerous neighborhoods if they don’t fork over a daily share of cash from bribes.

Officers usually don’t demand cash from the drivers they stop, he said. Instead, they start asking a lot of questions and reviewing registration records. Most people are quick to offer a bribe to avoid long dealings with officers who seem to have nothing but time on their hands.

“For Americans, $20 is nothing,” said the former officer. “The American has money. The American doesn’t know the law. The American doesn’t want his vacation delayed.”

The best way to avoid paying a bribe, he said, is to insist on being taken to the police station.

“If the American wanted to go to the station, I would follow for a while, and then put on my lights and pretend I had an emergency. I didn’t want to get in trouble with my supervisors,” the former patrol officer said.